#include<iostream>
#include<set>

//using namespace std;
//#include"open_address.h"
//#include"hash_bucket.h"
#include"my_unordered_map.h"
#include"my_unordered_set.h"
int main()
{
	//open_address::Test2();
	//hash_bucket::Test1();
	//shh::Test_unordered_set();
	//shh::test_unordered_set();
	set<int> s;
	int a[] = { 19,14,23,1,68,20,84,27,55,11,10,79 };
	for (auto& e : a)
		s.insert(e %= 7);
	cout << 12.0/s.size()<<endl;
	return 0;
}